184, HOMALOCRANIUM. ° 213 
shield. Body cylindrical ; scales smooth, without pits, in 15 rows ; 
ventrals rounded. ‘Tail moderate or short ; subcaudals in two rows. 
Southern North America; Central America; Tropical South 
America. 
Synopsis of the Species. 
I, Frontal not more than twice as broad as the posterior border of 
the supraocular; seven upper labials; two postoculars. 
A. Frontal hexagonal. 
1. Ventrals 120 or more. 
a. Two pairs of chin-shields. 
a. Rostral much broader than deep ; frontal considerably 
longer than broad. 
* Eye about half as long as the snout. 
t+ Frontal not more than once and a half as long as 
broad; subcaudals 46-71. 
First lower labial usually in contact 
with its fellow; seven upper labials ; [p. 215. 
body uniform or with dark stripes .. 1. melanocephalum, 
First lower labial in contact with its 
fellow ; seven upper labials; body 
with dark transverse spots or bars .. 2, annulatum, p. 217. 
Symphysial in contact with the anterior 
chin-shields ; eight upper labials ; body | 
with three light stripes............ 3. trilineatum, p. 217. 
Tt Frontal twice as long as broad; subcaudals 85. 
4. longifrontale, p. 218. 
** Hye not half as long as the snout. 
tT Posterior nasal in contact with or narrowly 
separated from the preocular. 
Ventrals 138-158 ; subcaudals 40-58.. 5. coronatum, p. 218. 
Ventrals 149-179; subcaudals 59-70.. 6. rubrum, p. 219. 
tt Posterior nasal very small and widely separated 
from the preocular.. 7. semicinctwm, p. 219. 
6. Rostral a little broader than deep. 
* First lower labial broadly in contact with its fellow ; 
eye not half as long as the snout. 
Frontal considerably longer than broad. 8. fuscum, p. 220. 
Frontal scarcely longer than broad .... 9. boulengeri, p. 221. 
** First lower labial separated from or narrowly in 
contact with its fellow. 
tT Eye not half as long as the snout; ventrals 121- 
135; subcaudals 32-38. 
10. schistosum, p. 221. 
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